Drying apparatus



Nov. 2 1926. 1,605,633 A. F. WRIGHT DRYING APPARATUS Filed July 9, .1919 2 Sheets-Sheet 1 lnvetor Z I By Attarne y Nov. 2 1926.

A. F. WRIGHT DRYING APPARATUS Filed July 9 1919 2 Sheets-Sheet 2 B [1Z5 Awctorrzeg attain eificiency,

Patented Nov. 2, .1926.

ARCHIBALD 1'. Warsaw, or EAST ORANGE, new JERSEY srenmnnrs, TO rm: mnvs'rnmr. DRYER conronn A conrom'rron or CONNECTICUT.

NECTICUT,

F] c E.

, ASSIGNOR, BY MESNE A8 TION, OF STAMFORD, CON- IDRYING APPARATUS.

Application filed July 9, 1918. Serial No. 809,705.

This invention pertains to an apparatus for drying materials, products, or substances of many kinds, and the object is to economy and rapidity in the elimination of moisture from the material under treatment.

Ordinary drying operations are conducted with a great loss of energy by reason of the discharge of the heated drying medium after it flows into contact with the material. The waste is due, first, to the heating of the drying medium to the desired working temperature which involves the expenditure of fuel and energy, and, second,,to the outflowing medium, more or less saturated with moisture, carrying with it a high percentage of heat.

Experience shows that in the drying of materials it is desirable to avoid that condition wherein a film is produced upon.

the surface of the material or substance under treatment, which condition is sometimes referred to as case hardening, and the presence of which surface film interferes to a marked extent with the free transudation of moisture, i. e. the moisture within the material is precluded by the film from D passing to the surface of such material in effecting the exchange of heat for moisture. In the present invention, the material under treatment is subjected to the action of a drying medium which carries a certain percentage of moisture together with the heat units required, whereby said material is kept in a condition for the free transndation of moisture and the heat in the drying medium is-exchanged the material, it having been found that certain materials respond to treatment more rapidlyand efficiently when the drying medium carries a certain percentage of moisture plus the required heat.

, To these-ends, the drying medium, usually air, is circulated and recirculated into contact with the material under treatment. In view of the fact that such repeated circulation of the drying medium eventually brings about an undesirable saturation of the air with moisture, I find it desirable to discharge a certain volume of the moistureladen air, and to replace the latter with a corresponding volume of fresh air, whereby the admixture of the inflowing fresh air.

with the moisture laden heated air acts to lated for moisture from and with a minimum expenditure l of the without.

of the surface film upon, or the case hardening of, the material under treatment.

In practicallycarrying out my invention, the drying medium is mechanically-circuby a blower or exhauster the intake of which is supplied in part with fresh air and in part with the moisture-laden heated air, provision being made for the discharge of a certain volume or proportion of the moisture laden air from the circulatory path of the drying medium. The admixture of the fresh air with the moisture laden heated air precludes an undesirable saturation of the drying medium by reason of the absorption of moisture from the material during the recirculation, while at the same time a large percentage of the heat and a certain percentage of the moisture are retained. uring such recirculation, the drying medium flows into contact with the material to effect theexchange of heat for moisture, and such medium during its recirculation may or may not be reheated dependent upon its condition and uponthe amount of moisture to be evaporated from the material.

'An apparatus for carrying out my invention is illustrated in the accompanying drawings, wherein- Fig. 1 is a sectional plan view of the apparatus, the plane of the section being indicated by the dotted line 1-1 of Fig. 2

Fig. 2 is a longitudinal vertical section on the line 2-2 of Fig. 1.

Fig. 3 is a transverse vertical section on the line 33 of Fig. 1.

Fig. 4 is a similar cross section through the lower part of the apparatus on the line 4-4 of 1.

A designates the housing, the interiorof which is divided by partitions a a to produce a plurality of treating chambers B a plurality of heating chambers so that the drying medium will flow successively through said chambers B C. The partitions a a are so related to each other and to the housing A that the inlets 0 and the outlets d from the heating chambers are at opposite sides of the housing, see Fig. 1, as a result of which 'the drying medium flows out of one treating chamber B into the adjacent heating chamber C.-

through the latter and into the next treating chamber B, through the latter chamber B and into the next heating chamber C, thereby directing the flow alternately through the treating chamber and the heating chamber.

Suitable means are employed for supporting the material within chambers B. As shown, wheeled trucks D are provided for carrying a stack of trays E within each chamber B, said trucks being movable through suitable doorways adapted to be tightly closed by appropriate doors 6. The trays are spaced relatively to each other upon the trucks to provide flow channels for the drying medium. It will be understood that material supporting means other than trays may be used for holding the material within the chambers B.

The chambers C are shown as containing heaters F for boosting the drying medium. These heaters may be of any desired character to be supplied with energy from a suitable source, such as steam, hot air, boiler room gases or other appropriate forms of heaters or boosters, but as shown the heaters are coils supplied with live steam from a main pipe F through branch pipes f.

Within the housing A near one end thereof is a partition 9 forming one wall to the first chamber B, and joined to this partition 7 is a cross partition h, the two partitions 9 la with certain walls of the housing A producing a mixing chamber G and a blower chamber H. A blower I of any appropriate style and of a desired capacity is situated within the chamber H, the pulley shaft i of said blower extending through a wall of housing A so as to receive a driving pulley i. The eye or intake j of said blower receives the drying medium to be circulated from the chamber H, whereas the wind trunk or outlet flue y" of said blower extends to and through the partition It so as to conduct the drying medium into the, mixing chamber G, see Figs. 1 and 3.

Communicating with the chamber H are a fresh air inlet K and the return flue L, whereby fresh air and a certain percentage of the circulating drying medium are conducted to the chamber H and thence to the blower intake, the volume of fresh air and of the circulating drying medium being con trollable by dampers K and L operable manually or in a desirable manner by appropriate means.

The return flue L is connected at one end to the last chamber C of the series of chambers within the housing, at the lower rear side thereof. Said return flue at the other end is in communication with fan chamber H and with an exhaust uptake M, the latter being shown as arranged outside of housing A, so that some of the returning moisture laden air will be permitted to escape into the uptake M whereas the major part of the returning moisture laden air is conducted by the flue L back to the fan chamber H, the volumes of the escaping air and of the returning air being controllable by adjustment of damper L in flue L and by the adjustment of damper M in the stackor uptake To indicate the moisture content of the circulation drying medium, a suitable hygrodeik (wet and dry thermometer) O is provided in the outlet pipe or uptake M, by observing which the operator is enabled to ascertain the percentage of moisture present in the circulating medium. Should this hygrodeik indicate an undesirably high per- ?entage of moisture, the damper M should be opened to a greater extent in order that m increased volume of such air may escape through uptake M, and at the same time the damper K should be opened to a greater extent in order to admit a correspondingly increased volume of fresh air through the intake K, the damper L being closed proportionately in order to cut down the volume of returning moisture laden air admitted by flue L to the fan chamber H.

In the drawings I have illustrated means for efi'ecting the thermostatic control of the live steam main F. A valve 77 in the main F has a rocker p to which is attached a rod 79 that leads to a thermostat P situated in the return flue L, see Fig. 3, said thermostat being responsive to a reduction in the temperature of the circulating drying medium in order to open the valve 2 and permit the inflow of live steam in a greater volume to the heaters F so that the temperature of the drying medium flowing into contact with the heaters will be raised as found necessary or desirable.

In operation, the material to be treated is loaded upon the trays E and trucks D are moved into chambers B. Steam is supplied by main pipe F to the heaters F and blower I is set in motion so as to effect the circulation of a current of air from the blower through wind trunk j, chambers G, B, C.

successively as indicated by the arrows, and

return flue L back to the fan chamber H and the exhaust flue M. Dampers K, L, M are adjusted according to the moisture content of the circulating drying medium.

The flow of the drying medium into contact with the material upon the trays E exchanges heat for moisture, and the contact of said drying medium with the coils F reheats the drying medium, so that the latter becomes heated to a certain degree and attains a certain saturation of moisture, the moisture content being indicated by the hygrodeik O. The air is thus circulated and recirculated in a definite path through the apparatus by the action of the blower, but according to this invention provision is made for the escape of a certain volumeof the moisture laden air returned by flue L through the .uptake M, (valve M being partially open) a larger percentage of the heated moisture laden air from said return flue L being conducted to the fan chamber H valve L being open more or less), and at t e same time the damper K is open to admit a corresponding volume of fresh air through the inlet K to the fan chamber H. The action of the blower thus draws in fresh air through inlet K and a certain percentage of the returning moisture laden and heated air from the flue L, the two flowing into the eye of the fan and being blown by said fan into the mixing chamber G, whence the mixed air is recirculated through chambers B C as described.

uring the recirculation of the drying medium for the evaporation of moisture from the material under treatment, the attendant should note the indication afforded by the hygrodeik O. In the event that the moisture content of the drying medium should become excessive, damper M should be opened more or less for the escape of the moisture laden air through the uptake M, whereas damper L should be correspondingly closed more or less to cut down the volume of heated and moisture laden air drawn into chamber H by the blower, and at the same time damper K should be opened for the admission of a larger volume of fresh air to chamber H, thus effecting a variation in the volumes of moisture laden air and the fresh air drawn into the blower and thence circulated by the latter through chambers G, B, C, the moisture laden heated air being mixed with the fresh air within b the chamber G. It will be understood that a large percentage of the heat units as well as the moisture in the circulating air are retained in the air drawn from flue L by the blower, and that this heated and moist air is mixed with the fresh air, thus utilizing the heat and moisture and effecting economy in the steam required for heating the circulating air to the temperature requiredrfor evaporating thematerial, the moisture present in the circulating air being carried to and in contact with the material so as to subject said material to such treatment as will preclude the presence or formation of a film on the surface of said material. .he admixture of fresh air in regulated volumes with the moist heated air keeps the drying medium in a condition for the eflicient and rapid evaporation of moisture from the material, whereas the utilization of the 'ditions, the outflow of warm moist air by recirculating it attains a most desirable economy in the energy expended for heating the drying medium to the required temperature.

In my invention provision is made for the control of the humidity as well as the temperature of the circulating drying medium,- the humidity condition'of the drying medium'being indicated by the wet and dry bulb thermometer O and such control of the humidity being attained by the discharge of a regulated or determined ing medium through the damper controlled stack M and also by feeding a regulated or determinedvolume of fresh air through the 'medium of the damper controlled inlet K. Assuming that it is desired to maintain the drying medium at, say saturation of moisture, and that for the first hour of operation the drying medium exchanges heat for moisture rapidly with a for example, 80% i volume of the drymoisture-laden material under treatment,

the damper M in the stack should be opened to an extent which permits a rather free outlet of the moisture-laden air, while at the same time the damper K in the inlet K is openedto a corresponding extent so as to feed fresh air in a determined volume eommensurate with or in proportion to the volume of moisture-laden airthus discharged, and also at the same time the damper L in the return flue is proportionately closed to permit the return of a reduced volume of air to the fan, so manipulations the volume of moist air returned to the fan is decreased whereas the volume of fresh air admitted is in proportion to the molst alr discharged, whereby the moist air mixed with the fresh air and recirculated by the fan is ina desired condition for exchanging heat for moisture. Now as the evaporation progresses and the moisture content of the material under treatment decreases, the dampers M K should e closed more or less in order to cut down the outflow of moist heated air and the inflow of the fresh air, respectively, whereas the damper L should be proportionatelv opened in order to return from the flue L to the fan a greater volume of moist heated air which becomes mixed with the reduced volume of the fresh air, so as to be recirculated by the fan and to be heated by the coils. It is apparent that under some conmoist heated air and the admixture therewith of fresh air can be cut off by adjustment of dampers M K, respectively, but under eration my invention makes provision for the regulation and control of the humiditv that as a result of these all conditions of opof the drying medium so as to maintain it at the desired working condition both as to humidity and temperature.

The procedure disclosed herein is useful in evaporating 'such materials as contain solvents with or without the addition to moisture, the subsequent recovery of which solvents is desirable from an industrial standpoint. The drying medium carrying the solvent to be recovered is discharged through the stack or uptake and thence conducted to a suitable apparatus wherein the drying medium is subjected to treatment in a suitable manner, as by compression or condensation, to separate and collect the solvents.

Having thus fully described the invention, what I claim as new, and desire to secure by Letters Patent is 1. In a drying mechanism, a material chamber, means including a blower for c1 rculating a drying medium within sald chamber, means for heating such drying medium, such circulation and heating of said medium imparting thereto predetermined proportions of temperature and moisture content, and means for maintaining such proportions of moisture content and temperature of such drying medium.

2. in a drying mechanism, a material chamber, means including a blower for recirculating a drying medium within said chamber whereby the drying medium is adapted to contain moisture to a certain extent, means for heating such drying medium whereby such medium is conditioned to determined proportions of temperature and humidity, and means for discharging moist air from, and feeding fresh air to, said drying medium for maintaining such proportions of temperature and humidity in said drying medium.

3. In a drying mechanism, a material chamber, means including a blower for recirculating a drying medium within said chamber, thermostatic-controlled means for heating such drying medium whereby said medium is conditioned as to temperature and humidity in determined proportions, and means for maintaining such proportions of temperature and humidity in such drying medium.

4. In a drying mechanism, a material chamber, means for circulating a drying medium within said chamber, means for heating suchdrying medium, means for conditioning such drying medium as to moisture content, and means whereby the temperature and the humidity of the drying medium are controllable for the maintenance of such temperature and humidity indefinite proportions.

5. In a drying mechanism, a material chamber, means for circulating a drying medium therein, means for heating such drying medium, and means whereby the temperature and the humidity of said drying medium are controllable for maintaining such temperature and humidity in definite proportions in such drying medium.

mosses 6. A drier embodying a chamber for the material under treatment, means for circulatlng a drying medium, means cooperating with said chamber and the circulating means for establishing a closed circulatory path for the drying medium whereby the latter in a moist heated condition may be circulated repeatedly within said closed path, means for indicating the moisture content of the drying medium adapted for circulatlon within said closed path, means for the escape from the circulatory path of a regulatable volume of the moist heated drying medium, and means for feeding to the circulatory path a regulatable volume of the drying medium from a source independent of the circulatory path.

7. A drier embodying a chamber for the material under treatment, means for circulating a dryingmedium, means cooperating with said chamber and the circulating means for establishing a closed circulatory path for the drying medium whereby the latter in a moist heated condition may be circulated repeatedly within said closed path, means within the circulatory path for heating the drying medium, means for the escape from the circulatory path of a regutatable volume of the moist drying medium, and means for feeding to the circulatory path a regulatable volume of the drying medium from a source independent of the circulatory path, such escape-controlling means and the feeding means co-operating with said heating means for the mainte nance of temperature and humidity in definite proportions within the drying medium.

8. A drier embodying a chamber for the material under treatment, means for circulating air, means cooperating with the chamber and the circulating means for establishing'a closed circulatory path for the air whereby moist air is returned to the circulating means, means for heating the air, means for the escape from the circulatory path of a regulated volume of moist air, and means for feeding fresh air to the circulatory path, said air-escaping means and air feeding means co-operating with the air heating means for the maintenance of temperature and humidity in definite proportions in the air circulated within said material chamber..

9. A drier embodying a chamber for the material under treatment, means for circulating air, means cooperating with said chamber and the circulating means for establishing a circulatory path for the air whereby moist air is returned to the circulating means, means within the circulatory path for heating air, a damper-controlled outlet for the escape from the circulatory path of a determined volume of the moist air, a controllable inlet for feeding to the circulatory path a regulatable volume of fresh air, and means whereby the air heating means and the air discharging and feeding means are adapted for control to effect the maintenance of the temperature and humidity in definite proportions in such circulating air.

10. A drier embodying a chamber for the material under treatment, a blower chamher, a return flue in communication with the material chamber and the blower chamber for establishing a circulatory path for the drying air,.means for heating air, a controllable outlet for moist air from the circulatory path, a controllable inlet for fresh air to the circulatory path, a thermostatic control for said air heating means, and means whereby the controllable outlet and the controllable inlet are adapted with the thermostatic control for said heating means to maintain in the drying air a definite proportion of temperature and moisture content.

11. A drier embodying material chamhers and heating chambers connected for the flow of a current of air successively within the same, a blower for circulating air, a return flue connected for receiving moist air from the chambers and for returning the moist air to the blower, heaters Within the heating chambers, a controllable outlet for the escape of moist air from the return flue, means for regulating the volume of moist air returning to the blower, and a controllable inlet for feeding fresh air to the moist heated air circulated by the blower.

12. A drier embodying a material chamber and a blower chamber, a flue connecting said chambers and establishing therewith a circulatory path for the drying medium, means for heating the drying medium,

means for indicating the moisture content of said drying medium, a controllable outlet for the escape from the circulatory path of a determined volume ofthe moist heated drying medium, a blower for circulating the drying medium, and a controllable inlet for feeding to the circulatory path a determined volume of the drying medium from a slpurce independent of the circulatory pat 13. A drier embodying material chambers and heating chambers connected for the flow of air successively within a closed circulatory path constituted by the chambers,

means for circulating air the outlet for which leads to said closed circulatory path, a return flue connected for receiving moist air from the chambers, a mixing chamber connected with said return flue for receiving a definite volume of moist air from said return flue, a controllable outlet for discharging moist air in a definite volume from the return flue, means for regulating the volume of moist air returned by said return flue to the mixing chamber, means for feeding fresh air to the mixing chamber, and controlling means for regulating the volume of fresh air admitted to the mixing chamber, the moist air returned by said flue and the fresh air admitted by the feeding means being separately supplied in determined volumes to the mixing chamber and thence flowing to the air circulating means by which the fresh air and moist air are intimately mixed and recirculated in such mixed condition within the closed circulatory path.

In testimony whereof I have hereunto signed my name this 27 day of June, 1919.

ARCHIBALD F. WRIGHT. 

